JP2001210571A - Method for forming alignment mark - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a new alignment mark, having a precise configuration for avoiding the affects of the ruggedness of a lower alignment mark and for avoiding a large expansion of an alignment mark formation area. SOLUTION: A method includes the steps of laminating a new interlayer film 3C on an interlayer film 3A on the undersurface, of which an alignment mark 2B is formed, subjecting the top surface to planarization, and forming a new alignment mark 2C in a portion 32, located directly above the alignment mark 2B of the top surface of the interlayer film 3C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for forming an alignment mark when a multilayer element is manufactured.

[0002]

2. Description of the Related Art In a multilayer film element such as a thin film magnetic head or a thin film integrated circuit, an insulating interlayer such as alumina or silica is laminated on a substrate and a circuit element is formed in the interlayer by a photolithography process. Has been done. Then, alignment marks are used for accurate positioning of the substrate and the photomask in such a process.

For example, when manufacturing a thin film magnetic head, a ceramic substrate 1 made of AlTiC or the like as shown in FIG.
After forming a separation layer such as a Cu material on the entire surface of the substrate, devices forming yokes of a NiFe material, coils and lead wires of a Cu material, wiring connection pads of an Au material, etc. are formed in a large number of shot regions 11 on the substrate 1 The portions are sequentially formed by a photolithography process using step-and-repeat exposure, and the device portions are laminated while being appropriately insulated from each other by an insulating interlayer film of alumina.

At this time, it is necessary to align the substrate 1 and the photomask so that the device pattern already formed on the substrate 1 and the projection pattern of the photomask accurately match each other. As shown in FIG. 7, an alignment mark forming area 13 is secured separately from the device forming area 12. In the alignment mark forming area 13, for example, a plurality of alignment marks 2 are formed at left and right symmetric positions, and a pair of alignment marks 2 which are usually at left and right symmetric positions are used for alignment.
One example of the alignment mark 2 is X, as shown in FIG.
A cross-shaped recess that allows positioning in two Y directions has 20
Within a square area of 0 μm, a width of about 2 to 5 μm and a depth of about 0.1 to
It is formed at 0.5 μm. In the cross-sectional views of the laminated film described below, the thickness of the device portion or the interlayer film and the depth of the alignment mark are drawn differently from the actual ratio for easy understanding.

[0005] By the way, device parts such as a yoke and a coil are formed by plating. In this case, as shown in FIG. Prior to this, a plating seed layer (a plating seed layer formed on the upper surface of the lower interlayer film 3B is indicated by reference numeral 4B) is formed on the upper surface of the interlayer film 3A. Since this plating seed layer does not transmit alignment light, the interlayer film 3A
The alignment mark 2B (hereinafter, referred to as a lower alignment mark) formed on the lower surface (the upper surface of the interlayer film 3B in contact with the device portion 5B) for forming the device portion 5B therein can be used for forming a new device portion 5A. And interlayer film 3A
It is necessary to newly form an alignment mark on the upper surface of the substrate.

However, if a new alignment mark is always formed at a position shifted from the lower alignment mark 2B in the plane direction (the left-right direction in FIG. 7), a wide alignment mark formation area 13 (FIG. 5) is secured. It is necessary to perform the device formation region 1 within the limited shot region 11.
2, there is a problem that the area that can be used effectively decreases. In particular, since the alignment marks are crushed in an etching or plating process for forming a device portion (for example, the lower alignment mark 2B in FIG. 7 is crushed by a plating layer), a plurality of alignment marks are usually formed for each interlayer film. It has been desired to solve the above problems.

For example, Japanese Patent Application Laid-Open No. H11-260682 proposes that a new alignment mark is formed immediately above the lower alignment mark to prevent the alignment mark formation area from expanding.

[0008]

However, although the upper surface of the interlayer film is usually flattened by mechanochemical polishing or the like for forming a new device portion, the upper surface of FIG.
As shown in (1), a minute uneven portion 31 may be formed on the upper surface portion of the interlayer film 3A located immediately above the lower alignment mark 2B due to the influence of the alignment mark 2B. Therefore, when a new alignment mark 2A slightly smaller than the uneven portion 31 is formed at the portion where the uneven portion 31 is formed as shown in FIG. There has been a problem that reflection and diffraction of light are disturbed, and accurate positioning of the photomask is hindered. In this case, it is difficult to predict the size of the uneven portion 31 and accurately form an alignment mark 2A that is exactly the same or slightly larger.

In view of the above, the present invention has been made to solve such a problem, and it is possible to form a new alignment mark with an accurate shape while avoiding the influence of the unevenness of the lower alignment mark, and to form an alignment mark forming area. An object of the present invention is to provide a method for forming an alignment mark that can avoid a large area enlargement.

[0010]

In order to achieve the above object, according to the present invention, there is provided an alignment method used for positioning a substrate when a multilayer film element is manufactured by laminating an interlayer film on a substrate by a photolithography process. In the method of forming a mark, at least one new interlayer film (3C) is laminated on the substrate or the interlayer film (3A) on which the alignment mark (2B) is formed on the lower surface while performing a planarization process. In a state where the influence of the unevenness of the mark (2B) is eliminated, a new alignment mark is formed on a portion (32) of the upper surface of the interlayer film (3C) located on the uppermost layer, which is located immediately above the alignment mark (2B). (2C) is formed.

In the present invention, at least one interlayer film is formed on the upper surface of the interlayer film having the alignment mark formed on the lower surface, and the upper surface is flattened.
A flat upper surface portion free from the influence of the unevenness can be obtained immediately above the alignment mark. Then, since a new alignment mark is formed on the upper surface portion, a new alignment mark can be formed at a position immediately above the alignment mark at least one layer in a state of being overlapped in a plane, and the alignment mark forming area can be greatly reduced. A large area enlargement can be avoided. Further, since the upper surface is flat, a new alignment mark can be formed with an accurate shape.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a sectional view of a laminated film in a shot region 11 (FIG. 5) to which the method of the present invention is applied. In FIG. 1, the fine upper and lower portions of the interlayer film 3A located directly above the lower alignment mark 2B are subjected to minute unevenness due to the influence of the alignment mark 2B even after the planarization as described in the related art. 31 results. Therefore,
A new alignment mark 2A is formed at a position displaced in the plane direction from the lower alignment mark 2B while avoiding the upper surface portion. Thereafter, a plating seed layer 4A is formed on the entire upper surface of the interlayer film 3A (FIG. 2 shows a plating seed layer remaining after removal, which will be described later), and a new device portion 5A is formed based on the alignment mark 2A. Then, the plating seed layer 4A between the device sections 5A is removed, a new interlayer film 3C is formed so as to cover them, and the upper surface thereof is flattened.

By performing the flattening process, minute uneven portions 3 caused by the influence of the lower alignment mark 2B are formed.
Since the upper surface portion 32 of the interlayer film 3C at the position immediately above the upper surface 1 has a flat surface with almost no unevenness, the upper surface portion 32 (that is, the position immediately above the lower alignment mark 2B) has an accurate shape as shown in FIG. New alignment mark 2C
Can be formed. Then, even after a plating seed layer (not shown) is formed, a new device portion 5C can be formed at an accurate position on the upper surface of the interlayer film 3C with reference to the new alignment mark 2C as shown by a chain line. .

As described above, according to the present embodiment, the upper surface of the interlayer film 3A having the lower alignment mark 2B formed on the lower surface is planarized, and the interlayer film 3C is further formed thereon to form the upper surface. Is flattened to obtain a flat upper surface portion 32 which is not affected by the unevenness just above the lower alignment mark 2B, and a new alignment mark 2C is formed there. Therefore, the upper surface portion 3 of the interlayer film just above the lower alignment mark 2B
2, a new alignment mark 2C can be formed in a state where the alignment mark 2C is superimposed on a plane, so that the area of the alignment mark forming region 13 (FIG. 5) can be prevented from being greatly increased, and the new alignment mark can be formed. 2
C can be formed in an accurate shape on the flat upper surface portion 32 of the interlayer film.

In the above embodiment, a new interlayer film 3C is formed on the interlayer film 3A having the lower alignment mark 2B formed on the lower surface, and a new alignment mark 2C is formed on the upper surface portion 32. However, the number of layers of the interlayer film to be stacked on the interlayer film 3A needs to be such that the flat upper surface portion 32 can be obtained without the influence of the unevenness of the lower alignment mark 2B. is not. In addition, the alignment mark is not limited to a concave mark, but may be a convex mark. In this case, as shown in FIG. In this case, the alignment marks 9 can be planar alignment marks 9 arranged in a cross shape. Further, the interlayer film 3B may be the substrate 1.

[0016]

As described above, according to the method of forming an alignment mark of the present invention, a new alignment mark can be formed in an accurate shape while avoiding the influence of the unevenness of the lower alignment mark. Significant area increase of the mark formation region can be avoided.

[Brief description of the drawings]

FIG. 1 is a conceptual sectional view of a laminated film, showing one embodiment of the present invention.

FIG. 2 is a conceptual sectional view of a laminated film, showing one embodiment of the present invention.

FIG. 3 is a conceptual cross-sectional view of a laminated film, showing one embodiment of the present invention.

FIG. 4 is a plan view of a ceramic substrate.

FIG. 5 is a conceptual plan view of a shot area.

FIG. 6 is a plan view of an alignment mark.

FIG. 7 is a conceptual cross-sectional view of a laminated film showing a conventional example.

FIG. 8 is a conceptual sectional view of a laminated film showing a conventional example.

FIG. 9 is a plan view showing another example of the alignment mark.

[Explanation of symbols]

1 ... substrate, 2B, 2C ... alignment mark, 3A, 3
C: interlayer film, 32: upper surface portion.

Claims (1)

[Claims] In a method of forming an alignment mark used for positioning the substrate when a multilayer film element is manufactured by a photolithography process by laminating an interlayer film on a substrate, the alignment mark is formed on a lower surface. At least one new interlayer film is stacked on the substrate or the interlayer film while performing a planarization process, and the top surface of the interlayer film located at this time is located in a state where the influence of the unevenness of the alignment mark is eliminated. Forming a new alignment mark in a portion located immediately above the alignment mark.